Summary of Congenital Cardiac Abnormalities
Cardiac abnormalities in children are predominantly congenital.
- Cardiac abnormalities are the largest group of congenital defects
- 8 per 1000 children have a significant congenital cardiac abnormality
- 1 in 10 still births have a cardiac abnormality
- 10-15% of cases have more than one abnormality
- 10-15% have another non-cardiac abnormality
- 80% of congenital cardiac abnormalities are one of the 9 main types (below)
- Mainly unknown
- 8% caused by chromosomal abnormality: E.g. Down’s syndrome, Edward’s syndrome, Patau’s syndrome, Turner’s syndrome, Williams syndrome
- Small proportion due to teratogenesis
- Increased risk(roughly 2x) if the parent has a congenital heart defect
- As they are sometimes associated with other genetic abnormalities (10-15%), it is worth considering echocardiography in a neonates with other abnormalities.
- Maternal illness
- Maternal drugs
Summary of the 9 main congenital heart defects
- Ventricular septal defect (VSD) – 30%
- Persistent Ductus Arteriosus – 12%
- Atrial septal defect (ASD) – 7%
Resulting in outflow obstruction
- Tetralogy of Fallot – 5%
- Transposition of the great arteries – 5%
- Complete atrioventricular septal defect
Cyanotic baby – a baby can be cyanotic even if it suffers from one of the acyanotic conditions, if the condition is severe enough, however, in the majority of cases, a cyanotic baby will be the result of one of the cyanotic heart conditions
- Cyanosis is more likely to occur when blood cannot get to the lungs, rather than when blood cannot be circulated around the body, thus it is more likely in right sided heart problems.
- Cyanosis is typically present where there is a right to left shunt
- Acyanotic disease is typically present when there is a left to right shunt – however – in pulmonary hypertension, the shunt can be reversed, and cyanosis can result.
Left heart pressure is higher than right heart pressure – after birth
Signs of decompensation:
- Poor feeding
- Engorged neck veins
- ↓pulse is a very poor prognostic sign!
- Weak pulse
- Cold peripheries
Presentations of Congenital Heart Defects
- Antenatally on USS
- Antenatally / neonatally with murmur
- In neonate with murmur
- In neonate with heart failure
- In neonate with shock
- All neonates scanned at 18-20 weeks for identification of abnormalities
- Detects 70% of cases that will subsequently require surgery in the first 6 months of life
- If an abnormality is detect, then fetal echocardiography can be performed for a detailed analysis
- If a defect is detected, parents can be offered counselling, and termination. The vast majority of mothers will chose to continue with delivery
- Usually soft (less than grade 3/6)
- Often position dependent – e.g. may be apparent when supine, but disappear when upright.
- Typically systolic but can be constant – throughout systole and diastole
- No palpable thrill
- No radiation
- Best heard at the left sternal edge
- More likely to be heard in febrile child – due to increased cardiac output
- Child otherwise well
- ECG and CXR normal
Some differentiate innocent murmurs into:
- Ejection murmur – caused by turbulent blood flow in the ventricles, outflow tracts, or great vessels on either side of the heart. No structural abnormality.
- Venous hum – turbulent blood flow in the veins of the head and neck. A continuous low pitched ‘hum’ best heard in the infraclavicular region, bilaterally. Amy be louder after exercise, and on inspiration.
- Disappears when lying flat, or when jugular vein is occluded – thus can be differentiated from PDA.
- Can be difficult to differentiate from pathological murmur – if in any doubt, then send for further analysis (ECG, echocardiogram, X-ray)
- Remember the signs as the 5 S’s: Soft, systolic, left Sternal edge, asymptomatic
Central cyanosis – is more closely associated to a cardiorespiratory abnormality
- Only visible when [Hb] >5 g/dl – thus may not be apparent in the anaemic child
- If in any doubt, use pulse oximetry to confirm PO2